/** Example 010 Shaders

This tutorial shows how to use shaders for D3D9, and OpenGL with the
engine and how to create new material types with them. It also shows how to
disable the generation of mipmaps at texture loading, and how to use text scene
nodes.

This tutorial does not explain how shaders work. I would recommend to read the
D3D or OpenGL, documentation, to search a tutorial, or to read a book about
this.

At first, we need to include all headers and do the stuff we always do, like in
nearly all other tutorials:
*/
#include <irrlicht.h>
#include <iostream>
#include "driverChoice.h"
#include "exampleHelper.h"

using namespace irr;

#ifdef _MSC_VER
#pragma comment(lib, "Irrlicht.lib")
#endif

/*
Because we want to use some interesting shaders in this tutorials, we need to
set some data for them to make them able to compute nice colors. In this
example, we'll use a simple vertex shader which will calculate the color of the
vertex based on the position of the camera.
For this, the shader needs the following data: The inverted world matrix for
transforming the normal, the clip matrix for transforming the position, the
camera position and the world position of the object for the calculation of the
angle of light, and the color of the light. To be able to tell the shader all
this data every frame, we have to derive a class from the
IShaderConstantSetCallBack interface and override its only method, namely
OnSetConstants(). This method will be called every time the material is set.
The method setVertexShaderConstant() of the IMaterialRendererServices interface
is used to set the data the shader needs. If the user chose to use a High Level
shader language like HLSL instead of Assembler in this example, you have to set
the variable name as parameter instead of the register index.
*/

IrrlichtDevice* device = 0;
bool UseHighLevelShaders = false;

class MyShaderCallBack : public video::IShaderConstantSetCallBack
{
public:
	MyShaderCallBack() : WorldViewProjID(-1), TransWorldID(-1), InvWorldID(-1), PositionID(-1),
						ColorID(-1), TextureID(-1)
	{
	}

	virtual void OnCreate(video::IMaterialRendererServices* services, s32 userData)
	{
		if (UseHighLevelShaders)
		{
			// Get shader constants id.
			// Constants are "uniforms" in most modern shading languages.
			// And they are not constant at all but can be changed before every draw call
			// (the naming probably has some historical reasons which got lost in time)
			WorldViewProjID = services->getVertexShaderConstantID("mWorldViewProj");
			TransWorldID = services->getVertexShaderConstantID("mTransWorld");
			InvWorldID = services->getVertexShaderConstantID("mInvWorld");
			PositionID = services->getVertexShaderConstantID("mLightPos");
			ColorID = services->getVertexShaderConstantID("mLightColor");

			// Textures ID are important only for OpenGL interface.
			video::IVideoDriver* driver = services->getVideoDriver();
			if(driver->getDriverType() == video::EDT_OPENGL)
				TextureID = services->getVertexShaderConstantID("myTexture");
		}

		// Set light color 
		// That could be set as well in OnSetConstants, but there's some cost to setting shader constants
		// So when we have non-changing shader constants it's more performant to set them only once.
		video::SColorf col(0.0f,1.0f,1.0f,0.0f);
		if (UseHighLevelShaders)
		{
			services->setVertexShaderConstant(ColorID, reinterpret_cast<f32*>(&col), 4);

			// Note: Since Irrlicht 1.9 it's possible to call setVertexShaderConstant 
			// from anywhere. To do that save the services pointer here in OnCreate, it
			// won't change as long as you use one IShaderConstantSetCallBack per shader
			// material. But when calling it ouside of IShaderConstantSetCallBack functions
			// you have to call services->startUseProgram()stopUseProgram() before/after doing so. 
			// At least for high-level shader constants, low level constants are not attached
			// to programs, so for those it doesn't matter.
			// Doing that sometimes makes sense for performance reasons, like for constants which
			// do only change once per frame or even less.
		}
		else
			services->setVertexShaderConstant(reinterpret_cast<f32*>(&col), 9, 1);
	}

	virtual void OnSetConstants(video::IMaterialRendererServices* services,
			s32 userData)
	{
		video::IVideoDriver* driver = services->getVideoDriver();

		// set inverted world matrix
		// if we are using highlevel shaders (the user can select this when
		// starting the program), we must set the constants by name.

		core::matrix4 invWorld = driver->getTransform(video::ETS_WORLD);
		invWorld.makeInverse();

		if (UseHighLevelShaders)
			services->setVertexShaderConstant(InvWorldID, invWorld.pointer(), 16);
		else
			services->setVertexShaderConstant(invWorld.pointer(), 0, 4);

		// set clip matrix

		core::matrix4 worldViewProj;
		worldViewProj = driver->getTransform(video::ETS_PROJECTION);
		worldViewProj *= driver->getTransform(video::ETS_VIEW);
		worldViewProj *= driver->getTransform(video::ETS_WORLD);

		if (UseHighLevelShaders)
			services->setVertexShaderConstant(WorldViewProjID, worldViewProj.pointer(), 16);
		else
			services->setVertexShaderConstant(worldViewProj.pointer(), 4, 4);

		// set camera position

		core::vector3df pos = device->getSceneManager()->
			getActiveCamera()->getAbsolutePosition();

		if (UseHighLevelShaders)
			services->setVertexShaderConstant(PositionID, reinterpret_cast<f32*>(&pos), 3);
		else
			services->setVertexShaderConstant(reinterpret_cast<f32*>(&pos), 8, 1);

		// set transposed world matrix

		core::matrix4 world = driver->getTransform(video::ETS_WORLD);
		world = world.getTransposed();

		if (UseHighLevelShaders)
		{
			services->setVertexShaderConstant(TransWorldID, world.pointer(), 16);

			// set texture, for textures you can use both an int and a float setPixelShaderConstant interfaces (You need it only for an OpenGL driver).
			s32 TextureLayerID = 0;
			services->setPixelShaderConstant(TextureID, &TextureLayerID, 1);
		}
		else
			services->setVertexShaderConstant(world.pointer(), 10, 4);
	}

private:
	s32 WorldViewProjID;
	s32 TransWorldID;
	s32 InvWorldID;
	s32 PositionID;
	s32 ColorID;
	s32 TextureID;
};

/*
The next few lines start up the engine just like in most other tutorials
before. But in addition, we ask the user if he wants to use high level shaders
in this example, if he selected a driver which is capable of doing so.
*/
int main()
{
	// ask user for driver
	video::E_DRIVER_TYPE driverType=driverChoiceConsole();
	if (driverType==video::EDT_COUNT)
		return 1;

	// ask the user if we should use high level shaders for this example
	if (driverType == video::EDT_DIRECT3D9 ||
		 driverType == video::EDT_OPENGL)
	{
		char i = 'y';
		printf("Please press 'y' if you want to use high level shaders.\n");
		std::cin >> i;
		if (i == 'y')
		{
			UseHighLevelShaders = true;
		}
	}

	// create device

	device = createDevice(driverType, core::dimension2d<u32>(640, 480));

	if (device == 0)
		return 1; // could not create selected driver.


	video::IVideoDriver* driver = device->getVideoDriver();
	scene::ISceneManager* smgr = device->getSceneManager();
	gui::IGUIEnvironment* gui = device->getGUIEnvironment();

	const io::path mediaPath = getExampleMediaPath();

	/*
	Now for the more interesting parts. If we are using Direct3D, we want
	to load vertex and pixel shader programs, if we have OpenGL, we want to
	use ARB fragment and vertex programs. I wrote the corresponding
	programs down into the files d3d9.ps, d3d9.vs, opengl.ps and opengl.vs. 
	We only need the right filenames now. This is done in the following switch. 
	Note, that it is not necessary to write the shaders into text files, 
	like in this example. You can even write the shaders directly as strings 
	into the cpp source file, and use later addShaderMaterial() instead of 
	addShaderMaterialFromFiles().
	*/

	io::path vsFileName; // filename for the vertex shader
	io::path psFileName; // filename for the pixel shader

	switch(driverType)
	{
	case video::EDT_DIRECT3D9:
		if (UseHighLevelShaders)
		{
			psFileName = mediaPath + "d3d9.hlsl";
			vsFileName = psFileName; // both shaders are in the same file
		}
		else
		{
			psFileName = mediaPath + "d3d9.psh";
			vsFileName = mediaPath + "d3d9.vsh";
		}
		break;

	case video::EDT_OPENGL:
		if (UseHighLevelShaders)
		{
			psFileName = mediaPath + "opengl.frag";
			vsFileName = mediaPath + "opengl.vert";
		}
		else
		{
			psFileName = mediaPath + "opengl.psh";
			vsFileName = mediaPath + "opengl.vsh";
		}
		break;
	case video::EDT_BURNINGSVIDEO:
		UseHighLevelShaders = true;
		psFileName = mediaPath + "opengl.frag";
		vsFileName = mediaPath + "opengl.vert";
		break;

	default:
		break;
	}

	/*
	In addition, we check if the hardware and the selected renderer is
	capable of executing the shaders we want. If not, we simply set the
	filename string to 0. This is not necessary, but useful in this
	example: For example, if the hardware is able to execute vertex shaders
	but not pixel shaders, we create a new material which only uses the
	vertex shader, and no pixel shader. Otherwise, if we would tell the
	engine to create this material and the engine sees that the hardware
	wouldn't be able to fulfill the request completely, it would not
	create any new material at all. So in this example you would see at
	least the vertex shader in action, without the pixel shader.
	*/

	if (!driver->queryFeature(video::EVDF_PIXEL_SHADER_1_1) &&
		!driver->queryFeature(video::EVDF_ARB_FRAGMENT_PROGRAM_1))
	{
		device->getLogger()->log("WARNING: Pixel shaders disabled "\
			"because of missing driver/hardware support.");
		psFileName = "";
	}

	if (!driver->queryFeature(video::EVDF_VERTEX_SHADER_1_1) &&
		!driver->queryFeature(video::EVDF_ARB_VERTEX_PROGRAM_1))
	{
		device->getLogger()->log("WARNING: Vertex shaders disabled "\
			"because of missing driver/hardware support.");
		vsFileName = "";
	}

	/*
	Now lets create the new materials. As you maybe know from previous
	examples, a material type in the Irrlicht engine is set by simply
	changing the MaterialType value in the SMaterial struct. And this value
	is just a simple 32 bit value, like video::EMT_SOLID. So we only need
	the engine to create a new value for us which we can set there. To do
	this, we get a pointer to the IGPUProgrammingServices and call
	addShaderMaterialFromFiles(), which returns such a new 32 bit value.
	That's all.

	The parameters to this method are the following: First, the names of
	the files containing the code of the vertex and the pixel shader. If
	you would use addShaderMaterial() instead, you would not need file
	names, then you could write the code of the shader directly as string.
	The following parameter is a pointer to the IShaderConstantSetCallBack
	class we wrote at the beginning of this tutorial. If you don't want to
	set constants, set this to 0. The last parameter tells the engine which
	material it should use as base material.

	To demonstrate this, we create two materials with a different base
	material, one with EMT_SOLID and one with EMT_TRANSPARENT_ADD_COLOR.
	The role of the base material is to set the alpha (transparency)
	and blending settings as used in the base material. Avoid the 
	EMT_NORMAL_... or EMT_PARALLAX... types as base materials as they
	are internally shaders themselves and will only create conflicts with 
	your shaders.
	*/

	// create materials

	video::IGPUProgrammingServices* gpu = driver->getGPUProgrammingServices();
	s32 newMaterialType1 = 0;
	s32 newMaterialType2 = 0;

	if (gpu)
	{
		/*
		Create one callback instance for each shader material you add.
		Reason is that the getVertexShaderConstantID returns ID's which are
		only valid per added material (The ID's tend to be identical
		as long as the shader code is exactly identical, but it's not good
		style to depend on that).
		*/
		MyShaderCallBack* mcSolid = new MyShaderCallBack();
		MyShaderCallBack* mcTransparentAdd = new MyShaderCallBack();

		// create the shaders depending on if the user wanted high level
		// or low level shaders:

		if (UseHighLevelShaders)
		{
			// create material from high level shaders (hlsl, glsl)

			newMaterialType1 = gpu->addHighLevelShaderMaterialFromFiles(
				vsFileName, "vertexMain", video::EVST_VS_1_1,
				psFileName, "pixelMain", video::EPST_PS_1_1,
				mcSolid, video::EMT_SOLID, 0);

			newMaterialType2 = gpu->addHighLevelShaderMaterialFromFiles(
				vsFileName, "vertexMain", video::EVST_VS_1_1,
				psFileName, "pixelMain", video::EPST_PS_1_1,
				mcTransparentAdd, video::EMT_TRANSPARENT_ADD_COLOR, 0);
		}
		else
		{
			// create material from low level shaders (asm or arb_asm)

			newMaterialType1 = gpu->addShaderMaterialFromFiles(vsFileName,
				psFileName, mcSolid, video::EMT_SOLID);

			newMaterialType2 = gpu->addShaderMaterialFromFiles(vsFileName,
				psFileName, mcTransparentAdd, video::EMT_TRANSPARENT_ADD_COLOR);
		}

		mcSolid->drop();
		mcTransparentAdd->drop();
	}

	/*
	Now it's time for testing the materials. We create a test cube and set
	the material we created. In addition, we add a text scene node to the
	cube and a rotation animator to make it look more interesting and
	important.
	*/

	// create test scene node 1, with the new created material type 1

	scene::ISceneNode* node = smgr->addCubeSceneNode(50);
	node->setPosition(core::vector3df(0,0,0));
	node->setMaterialTexture(0, driver->getTexture(mediaPath + "wall.bmp"));
	node->setMaterialFlag(video::EMF_LIGHTING, false);
	node->setMaterialType((video::E_MATERIAL_TYPE)newMaterialType1);

	smgr->addTextSceneNode(gui->getBuiltInFont(),
			L"PS & VS & EMT_SOLID",
			video::SColor(255,255,255,255),	node);

	scene::ISceneNodeAnimator* anim = smgr->createRotationAnimator(
			core::vector3df(0,0.3f,0));
	node->addAnimator(anim);
	anim->drop();

	/*
	Same for the second cube, but with the second material we created.
	*/

	// create test scene node 2, with the new created material type 2

	node = smgr->addCubeSceneNode(50);
	node->setPosition(core::vector3df(0,-10,50));
	node->setMaterialTexture(0, driver->getTexture(mediaPath + "wall.bmp"));
	node->setMaterialFlag(video::EMF_LIGHTING, false);
	node->setMaterialFlag(video::EMF_BLEND_OPERATION, true);
	node->setMaterialType((video::E_MATERIAL_TYPE)newMaterialType2);

	smgr->addTextSceneNode(gui->getBuiltInFont(),
			L"PS & VS & EMT_TRANSPARENT",
			video::SColor(255,255,255,255),	node);

	anim = smgr->createRotationAnimator(core::vector3df(0,0.3f,0));
	node->addAnimator(anim);
	anim->drop();

	/*
	Then we add a third cube without a shader on it, to be able to compare
	the cubes.
	*/

	// add a scene node with no shader

	node = smgr->addCubeSceneNode(50);
	node->setPosition(core::vector3df(0,50,25));
	node->setMaterialTexture(0, driver->getTexture(mediaPath + "wall.bmp"));
	node->setMaterialFlag(video::EMF_LIGHTING, false);
	smgr->addTextSceneNode(gui->getBuiltInFont(), L"NO SHADER",
		video::SColor(255,255,255,255), node);

	/*
	And last, we add a skybox and a user controlled camera to the scene.
	For the skybox textures, we disable mipmap generation, because we don't
	need mipmaps on it.
	*/

	// add a nice skybox

	driver->setTextureCreationFlag(video::ETCF_CREATE_MIP_MAPS, false);

	smgr->addSkyBoxSceneNode(
		driver->getTexture(mediaPath + "irrlicht2_up.jpg"),
		driver->getTexture(mediaPath + "irrlicht2_dn.jpg"),
		driver->getTexture(mediaPath + "irrlicht2_lf.jpg"),
		driver->getTexture(mediaPath + "irrlicht2_rt.jpg"),
		driver->getTexture(mediaPath + "irrlicht2_ft.jpg"),
		driver->getTexture(mediaPath + "irrlicht2_bk.jpg"));

	driver->setTextureCreationFlag(video::ETCF_CREATE_MIP_MAPS, true);

	// add a camera and disable the mouse cursor

	scene::ICameraSceneNode* cam = smgr->addCameraSceneNodeFPS();
	cam->setPosition(core::vector3df(-100,50,100));
	cam->setTarget(core::vector3df(0,0,0));
	device->getCursorControl()->setVisible(false);

	/*
	Now draw everything. That's all.
	*/

	int lastFPS = -1;

	while(device->run())
		if (device->isWindowActive())
	{
		driver->beginScene(video::ECBF_COLOR | video::ECBF_DEPTH, video::SColor(255,0,0,0));
		smgr->drawAll();
		driver->endScene();

		int fps = driver->getFPS();

		if (lastFPS != fps)
		{
			core::stringw str = L"Irrlicht Engine - Vertex and pixel shader example [";
			str += driver->getName();
			str += "] FPS:";
			str += fps;

			device->setWindowCaption(str.c_str());
			lastFPS = fps;
		}
	}

	device->drop();

	return 0;
}

/*
Compile and run this, and I hope you have fun with your new little shader
writing tool :).
**/